Might be a stupid question, but will 77mm barrels go into a 1600 case, like a new alluminium case? Might have a crack in my case have to see but am looking at options, was wanting a aluminium case so I can upgrade the barrels etc in a few years time... the motor is a stock 1300 at the moment

hey mate i don't think they will
and if you going to the trouble of building up an engine with new case and all the work that goes into it just buy new 85.5 pistons rings barls etc about 200 - 250 cheap as chip but you will also need new heads
id try buying a new long block! maybe give rod penrose a try??
i remember see new mexo long block for 2100 but i think there upto 2500 not sure
if you going to build one up
700 new case
maybe use your old crank grind back and new bearing
id run a new cam 150 bux new bearing all round
pistons 200-250
heads 250 each X2
oil pump
gasket kit
and it all ad up and that using 40 year old parts to save a little money!

cheers mate